No, you are not overreacting at all. I am severly allergic to smoke and I will not let someone who smokes any where near my children. I get SO irate when I go to walk into a store and it reaks of smoke by the entrance. I proceed directly to the manager and complain. There needs to be a law that you can not smoke within 500yards of a door, whether it be store, restaurant, or what ever it is. I tell my kids to hold their breath and run through as fast as possible, but we are still putting our bodies and clothes through the smoke.

Even if you have them change clothes and wash hands, the smoke is still in their skin.

What would you personally do in this type situation? Just tell them there're not allowed near your children? Or is there some kind of compromise? Of course with you having an actual allergy, it does change the picture quite a bit.